IBM i Fundamentals

An ordered path through the foundational IBM i concepts every beginner and working developer benefits from knowing.

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Showing 16 of 288 lessons

81What is a Subfile in IBM i?Log in to accessWhy subfiles exist: showing a scrollable list of multiple records on one 5250 screen, instead of just one record at a time.
82Subfile Record Format vs Subfile Control Record FormatLog in to accessThe key distinction between a subfile record format (SFL, one repeating row) and its control record format (SFLCTL, the frame).
83SFLDSP, SFLDSPCTL, and SFLCLR ExplainedLog in to accessWhat SFLDSP, SFLDSPCTL, and SFLCLR each control, and how RPGLE uses conditioning indicators to manage a subfile lifecycle.
84Load-All Subfile ConceptLog in to accessThe load-all subfile strategy: loading every record before displaying it once, and how SFLPAG and SFLSIZ relate to it.
85Page-at-a-Time Subfile ConceptLog in to accessThe page-at-a-time subfile strategy at a conceptual level, how it differs from load-all, and the role of RRN.
86Simple Inquiry Subfile PatternLog in to accessA complete, simple RPGLE program that clears, loads, and displays a load-all subfile showing a list of records.
87Function Keys in Subfile ProgramsLog in to accessWhich function keys a load-all subfile handles automatically (Page Up/Down), and how custom function keys still work the same way.
88Common Subfile Mistakes and Best PracticesLog in to accessCommon beginner mistakes with subfiles, such as misplaced fields, forgetting to clear before reload, and premature SFLDSP.
89Understanding RRN in Subfile ProgramsLog in to accessWhat the Relative Record Number (RRN) actually is, and how SFLRCDNBR lets a program reliably identify a subfile row.
90Clearing and Reloading a SubfileLog in to accessWhy a subfile commonly needs to be cleared and reloaded more than once during a program run, such as on a refresh.
91Using SFLEND to Show End of ListLog in to accessWhat SFLEND does: automatically showing More... or Bottom so users know whether more subfile records remain.
92Option Fields in Subfile ScreensLog in to accessWhat an option field is, how it lets a user choose an action per row, and common conventions like 1=Select, 2=Change, 4=Delete.
93Selecting a Row in a SubfileLog in to accessHow to use READC in a loop to find every subfile row a user entered an option value on, and read each one's RRN.
94Basic Update/Delete Subfile PatternLog in to accessThe general, conceptual flow behind a subfile screen that lets a user update or delete records marked with option values.
95Introduction to SFLNXTCHGLog in to accessWhat SFLNXTCHG does at a conceptual level: letting a program mark a subfile row as changed so READC finds it again.
96Debugging Subfile ProgramsLog in to accessBeginner-friendly ways to investigate a subfile program: checking clear/load/display indicators, loading loops, and READC.